The stricken coaster Carrier, which ran aground off north Wales, has been losing fuel after rocks ripped three holes in the hull.

All seven of the Polish crew were evacuated by helicopter amid high seas and gales at about 1am on Wednesday. Although the Marine and Coastguard Agency (MCA) confirmed the fuel loss, it added that the hull immediately around the fuel tank remained intact.

The caergo ship, carrying 40,000 litres of gas oil, ran aground at 8pm on Tuesday on the beach next to Raynes Jetty at Llanddulas, near Colwyn Bay, where it was damaged while taking on board a cargo of limestone.

The weather abated slightly on Wednesday, but there were still force eight winds and heavy rain.

"We know that there has been a quantity of fuel lost. We just don't know how much yet," said Ray Carson, rescue co-ordination centre manager at Holyhead Coastguard.

"It is still fairly wild out there. She is rising and falling and buffering against the concrete defences."

A team of salvage and pollution experts were making their way to the site from the agency's offices in Walton-on-the-Naze, Essex, to remove the fuel as quickly as possible.

The A55, which is adjacent to the jetty, continued to be closed but North Wales police planned to reopen the westbound carriageway and one lane of the eastbound trunk road as soon as possible.

Assistant Chief Constable Gareth Pritchard said: "We apologise for the inconvenience caused to the public but safely managing this incident is our priority."

At 10am on Wednesday, an emergency "gold-level" meeting of HM Coastguard, North Wales fire and rescue service, police, local authorities and the Trunk Road Agency took place to discuss how to secure the ship.

The MCA has to decide whether to move the Carrier before repairing the damage. Gas oil, which is similar to diesel, is not as polluting as fuel oil.

The 82-metre (269ft) ship is also partially loaded with limestone, making her harder to move. Her capacity is 1,587 tons.

"The facility [on the jetty] is in effect a conveyor belt – and they can't just put the conveyor belt in reverse," Carson said.

The ship's proximity to the A55 could also hamper a rescue effort. A solution could be to install a contraflow while work is done to make the Carrier safe. A wide coastal path could also be used as a place from which to make repairs.

The seven crew, who were taken to local accommodation following the rescue, were safe and well. There was no need for medical assistance.

"From a coastguard perspective, we did our best. We got the crew out without even getting their feet wet, which was good," Carson said.

Although it was not known exactly how the vessel ran aground, it was thought that damage was done as the ship was buffeted by winds while trying to move off the jetty after loading its cargo.

The grounding comes after another vessel – the Swanland – got into difficulties and sank on 27 November 2011 after loading with limestone at Raynes Jetty.